Browning made his MLB debut in 2012, appearing in 22 games out of the bullpen for the Cardinals and posting a 5.12 ERA with 5.1 K/9 and 3.3 BB/9. The 28-year-old spent much of the season at Triple-A, posting a 1.73 ERA with 8.2 K/9 and 3.9 BB/9 in 41 2/3 innings.